Weighted part of golf club head

ABSTRACT

A weighted part of a golf club head is provided. The compositions of the weighted part by weight percent are 12% to 15% iron, 11% to 13% chromium, 25% to 30% tungsten, and some nickel. The alloy for the weighted part has the advantages of being heavier than stainless steel and titanium alloys in weight, enjoying higher tensile strength, providing higher plastic deformation for the weighted part, and forming more complicated trademarks or patterns directly at specific locations during weighted part formation. In addition, the mechanical properties of the weighted part of a golf club head can be improved by adding ingredients including carbon below 0.01%, 0.1% to 0.6% silicon, manganese below 0.01%, phosphorus below 0.01%, sulphur below 0.01%, and copper below 0.01%.

This application is a continuation-in-part of co-pending application U.S. application Ser. No. 11/842,272 filed Aug. 16, 2007 which claims the benefit of Taiwan Patent Application No. 096123807, filed on Jun. 29, 2007, and this application also claims the benefit of Taiwan Patent Application No. 097121240, filed on Jun. 6, 2008, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a weighted part of a golf club head, and more particularly, to a golf club head's alloyed weighted part capable of enjoying higher tensile strength and specific gravity.

2. Description of the Prior Art

A conventional gold club head is formed by a back sole, a club face, a top, and a neck, wherein the neck is inserted into a shaft, thus leading to twisting during swinging. To prevent torsion created during swinging, enhance swing smoothness and maintain a good impact, the golf club head must have a lower center of gravity and a suitable weighted part location. A conventional golf club head mostly includes a weighted part attached to a lower-half portion at a back of the golf club head fabricated through powder metallurgy, in which weights in the shape of pieces, tablets or cylinders are fabricated from tungsten (W)-nickel (Ni)-iron (Fe) alloys or tungsten (W)-nickel (Ni)-copper (Cu) alloys. A weighted part is securely attached to a corresponding location at the back sole of the golf club head by insertion, locking, soldering, welding, riveting or gluing.

The above weighting of the golf club head is formed by fixing a plurality of weights of high specific gravity at the required locations. By doing so, the golf head's center of gravity is properly adjusted through the distribution of weights at diverse locations. However, given that both the golf club head's weight restrictions (in terms of heaviness) and the requirements for its center of gravity should be considered, weighting is usually calculated using computers. Several adjustments must be made to satisfy the golf club head's requirements for a high specific gravity and a low center of gravity. General golf club head's weights are usually made of aluminum-bronze alloys and tungsten-iron-nickel alloys, wherein tungsten-iron-nickel alloys (tungsten: iron: nickel=19.3 g/cm³: 7.8 g/cm³: 8.9 g/cm³) characterized by their heaviness, small volume and high hardness have widely used in industrial applications. Generally, weighted parts made of tungsten-iron-nickel alloys are fabricated through powder metallurgy, whereby metallic powders at pre-determined proportions are mixed and compressed into samples that are sintered at a high temperature (and in a vacuum environment) and are subject to further processing and thermal treatment, in order to fabricate weighted parts. Nonetheless, several drawbacks are inherent in the above prior art, such as high molding costs, a lower elongation percentage achieved for the product, longer fabrication time, and the failure to form refined trademarks, patterns, letters and characters and model numbers directly through compression. Due to the composition of extremely hard tungsten metals in the tungsten-iron-nickel weighted parts, exquisite trademarks and patterns can hardly be fabricated. However, if the weighted parts are engraved after sintering, their productivity will be negatively affected.

In addition, some manufacturers fabricate tungsten-iron-nickel weighted parts through precision casting, in order to overcome the incapability of powder metallurgy to form exquisite patterns directly through compression. Nonetheless, given the unnecessary forming of tungsten precipitates obtained by melting high-melting-point tungsten through precision casting, precision casting is not widely used for the fabrication of tungsten-iron-nickel weighted parts, despite its advantages of lower production costs, a higher elongation percentage achieved for the weighted part, shorter fabrication time and the capability of forming exquisite patterns directly through casting.

SUMMARY OF THE INVENTION

To overcome the above drawbacks, an object of the present invention is to provide a type of modified tungsten-iron-nickel alloys capable of directly applying one-shot molding for the fabrication of weighted parts through precision casting.

Another object of the present invention is to provide a golf club head's weighted part comprising by weight percent: 12% to 15% iron, 11% to 13% chromium, 25% to 30% tungsten, and some nickel.

The present invention may further include carbon below 0.01%, 0.1% to 0.6% silicon, manganese below 0.01%, phosphorus below 0.01%, sulphur below 0.01%, and copper below 0.01%, so as to improve the mechanical properties of the weighted part of a golf club head.

According to a preferred embodiment of the present invention, the weighted part is formed by fully melting and evenly stirring all the metals, forming an ingot through melting, melting the ingot through precision casting, injecting the melted ingot into a precision casting shell, and taking out the finished weighted part from the precision casting shell until the melted ingot is cooled.

The specific gravity of the weighted part preferably lies between 9 and 12 g/cm³, wherein the elongation percentage of its materials lies between 49 and 69%.

The weighted part is preferably integrated into the shape of a back sole of the golf club head.

The weighted part preferably includes at least a convex portion which is thicker than the other parts of the weighted part in thickness; or at least a concave portion which is thinner than the other parts of the weighted part in thickness.

The convex portion of the weighted part is preferably disposed on an inner surface thereof.

The concave portion of the weighted part is preferably disposed on an inner surface thereof.

The weighted part is securely attached to a corresponding location at the back sole of the golf club head by locking, welding, Tungsten-Inert-Gas (TIG) welding, high-energy electron beam welding, soldering or gluing.

The advantage of the present invention is the capability of forming an integrated weighted part in a pre-determined shape through precision casting which is designed by using computer software. Given the integrated structure made of evenly-textured materials, the materials are highly integrated with satisfactory mechanical properties. Additionally, the advantages of the present invention are (1) the forming of an integrated mold design through precision casting of extremely hard tungsten as well as nickel of high elongation percentage, and (2) the forming of exquisite trademarks or patterns at appropriate locations (by analyzing the center of gravity of the weighted part with computer-aid analysis while forming weighted part.

To enable a further understanding of the objectives and the technological methods of the invention herein, the brief description of the drawings below is followed by the detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWING

The single FIGURE shows a metallographic structure of an embodiment illustrating two-point sampling for the weighted part made according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A golf club head's weighted part disclosed in the present invention is securely positioned to the golf club head comprising by weight percent: 12% to 15% iron, 11% to 13% chromium, 25% to 30% tungsten, and some nickel. Moreover, the weighted part of a golf club head of the present invention may further comprise additional ingredients including carbon below 0.01%, 0.1% to 0.6% silicon, manganese below 0.01%, phosphorus below 0.01%, sulphur below 0.01%, and copper below 0.01% for improving the mechanical properties of the weighted part. Referring to FIG. 1, they are metallographic images of the present invention.

The specific gravity of the weighted part preferably lies between 9 to 12 g/cm³, wherein the elongation percentage of its materials lies between 49 to 69%.

According to Embodiment 1 of the following weighted part, its compositions by weight percent are 0.0086% carbon, 0.18% silicon, 0.009% manganese, 0.005% phosphorus, 0.002% sulphur, 12.83% iron, 11.05% chromium, 0.009% copper, 25.5% tungsten, and some nickel. Then three-stage samples of Embodiment 1 are taken out and numbered as Sample No. 1, Sample No. 2 and Sample No. 3 respectively. Refer to Table 1 for the testing data on the analysis of properties of these three samples.

TABLE 1 Testing Report Testing Items R_(m),R_(p0.2),A,HRB,p Proof Strength Elongation at Non- Percentage Tensile Proportional after Rockwell Sample Strength Extension Fracture hardness Density No. (R_(m)/MPa) (R_(p0.2)/MPa) (A/%) (HRB) (p/g.cm³) 1 665 296 67.0 82.0 10.03 2 660 288 69.0 79.0 3 658 298 66.0 83.0

According to Embodiment 2 of the following weighted part, its compositions by weight percent are 0.0088% carbon, 0.16% silicon, 0.01% manganese, 0.005% phosphorus, 0.0021% sulphur, 13.14% iron, 11.36% chromium, 0.01% copper, 25.80% tungsten, and some nickel. Then three-stage samples of Embodiment 2 are taken out and numbered as Sample No. 4, Sample No. 5 and Sample No. 6 respectively. Refer to Table 2 for the testing data on the analysis of properties of these three samples.

TABLE 2 Testing Report Testing Items R_(m),R_(p0.2),A,HRB,p Proof Strength Elongation at Non- Percentage Tensile Proportional after Rockwell Sample Strength Extension Fracture hardness Density No. (R_(m)/MPa) (R_(p0.2)/MPa) (A/%) (HRB) (p/g.cm³) 4 700 310 63.0 88.0 10.03 5 665 305 58.0 87.0 6 725 340 50.5 87.5

According to Embodiment 3 of the following weighted part, its compositions by weight percent are 0.0092% carbon, 0.27% silicon, 0.01% manganese, 0.006% phosphorus, 0.0044% sulphur, 14.33% iron, 12.65% chromium, 0.01% copper, 28.77% tungsten, and some nickel. Then three-stage samples of Embodiment 3 are taken out and numbered as Sample No. 7, Sample No. 8 and Sample No. 9 respectively. Refer to Table 3 for the testing data on the analysis of properties of these three samples.

TABLE 3 Testing Report Testing Items R_(m),R_(p0.2),A,HRB,p Proof Strength Elongation at Non- Percentage Tensile Proportional after Rockwell Sample Strength Extension Fracture hardness Density No. (R_(m)/MPa) (R_(p0.2)/MPa) (A/%) (HRB) (p/g.cm³) 7 727 328 55.0 90.0 10.05 8 718 351 49.0 92.0 9 715 355 52.0 96.0

The above method of fabricating weighted parts includes the steps of fully melting and evenly stirring all the metals, forming an ingot through melting, melting the ingot through precision casting, injecting the melted ingot into a precision casting shell, and taking out the finished weighted part from the precision casting shell until the melted ingot is cooled.

The weighted part includes at least a convex portion and/or at least a concave portion that are configured on the basis of several factors (size, quantity and location) to match the weighted part of the golf club head, in order to achieve the required center of gravity.

The weighted part is securely attached to a corresponding location at the back sole of the golf club head by locking, welding, Tungsten-Inert-Gas (TIG) welding, high-energy electron beam welding, soldering or gluing.

It is of course to be understood that the embodiment described herein is merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims. 

1. A weighted part of a golf club head, securely attached to said golf club head comprises by weight percent 12% to 15% iron, 11% to 13% chromium, 25% to 30% tungsten, and some nickel.
 2. The weighted part of a golf club head as claimed in claim 1, further comprising ingredients including carbon below 0.01%, 0.1% to 0.6% silicon, manganese below 0.01%, phosphorus below 0.01%, sulphur below 0.01%, and copper below 0.01% for improving the mechanical properties of said weighted part.
 3. The weighted part of a golf club head as claimed in claim 1, wherein the specific gravity of said weighted part is 9 to 12 g/cm³, and the elongation percentage of its materials is 49 to 69%.
 4. The weighted part of a golf club head as claimed in claim 1, wherein said weighted part is integrated into the shape of a back sole of said golf club head.
 5. The weighted part of a golf club head as claimed in claim 1, wherein said weighted part comprises at least a convex portion that is thicker than the other parts of said weighted part in thickness.
 6. The weighted part of a golf club head as claimed in claim 1, wherein said weighted part comprises at least a concave portion that is thinner than the other parts of said weighted part in thickness.
 7. The weighted part of a golf club head as claimed in claim 5, wherein said convex portion of said weighted part is disposed on an inner surface thereof.
 8. The weighted part of a golf club head as claimed in claim 6, wherein said concave portion of said weighted part is disposed on an inner surface thereof.
 9. The weighted part of a golf club head as claimed in claim 1, wherein said weighted part is securely attached to a corresponding location at said back sole of said golf club head by locking, welding, Tungsten-Inert-Gas (TIG) welding, high-energy electron beam welding, soldering or gluing. 